[time-nuts] Question about SoundCard stability?

Magnus Danielson magnus at rubidium.dyndns.org
Wed Oct 13 08:00:56 UTC 2010


On 10/13/2010 05:32 AM, Jim Lux wrote:
>
>
> On Oct 12, 2010, at 6:09 PM, Magnus Danielson<magnus at rubidium.dyndns.org>  wrote:
>
>> Hi Bob and Dave,
>>
>> On 10/13/2010 02:57 AM, Bob Camp wrote:
>>> Hi
>>>
>>> Yes it is a reasonable expectation as long as you don't have a lot of drafts. A good TCXO can get down to sub 0.1 ppb over that period.
>>
>> This is why I like ADEV plots in datasheets. I rarely get to see them. TDEV plots is a nice complement naturally.
>>
>> Cheers,
>> Magnus
>>
>>> Bob
>>>
>
> And I wish there were adev plots for cheap tcxo's on the mgr data sheets

Me too. I have to make the measurement myself. In one case I found that 
the oven control in one OCXO was unstable and had a resonance at about 7 
second period. It was possible to measure it on the current supply too. 
The oven-control was having a relatively high-Q resonance and 
self-oscillation around the stability point. It increased the ADEV at 
that point to almost about 10 times more than expected. I learned that 
it was a good thing I measured it and yes, that spec didn't exist in the 
datasheet. It is unclear if they knew it or not. Even my half-crap setup 
proved valueable as I got aware of an issue on sample level rather than 
out in production phase.

Cheers,
Magnus



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